Hi Landon,
GGG and Pine Creek are correct if you are using the DCS Remote Commander.
If you are using the DCS Commander...
You could have a polarity issue with your engines. The DCS Commander on outputs DC current. Three volt PS2 and PS3 engines will run fine on DC current and should work if your DCS Commander is setup properly. Earlier 5 volt PS2 engines will also run on DC current, but they are polarity sensitive. They need to have the positive voltage wired to the center rail and the negative (ground) wired to the outside rails. The DCS Commander has a built in polarity switch for running in conventional DC mode. If you are using a 5 volt engine try swapping the output wires or entering conventional mode (CONV button), pressing the red direction button, and switching back to DCS mode (DCS button).